Mycology Book
Heli Whetzel
Mycology is the branch of biology concerned with the study of fungi, including their taxonomy, genetics, biochemical properties, and use by humans. Fungi can be a source of tinder, food, traditional medicine, as well as entheogens, poison, and infection. Mycology branches into the field of phytopathology, the study of plant diseases. The two disciplines are closely related, because the vast majority of plant pathogens are fungi. A biologist specializing in mycology is called a mycologist.
Although mycology was historically considered a branch of botany, the 1969 discovery[1] of fungi's close evolutionary relationship to animals resulted in the study's reclassification as an independent field.[2] Pioneer mycologists included Elias Magnus Fries, Christiaan Hendrik Persoon, Heinrich Anton de Bary, Elizabeth Eaton Morse, and Lewis David de Schweinitz. Beatrix Potter, author of The Tale of Peter Rabbit, also made significant contributions to the field.[3]
Pier Andrea Saccardo developed a system for classifying the imperfect fungi by spore color and form, which became the primary system used before classification by DNA analysis. He is most famous for his Sylloge Fungorum,[4] which was a comprehensive list of all of the names that had been used for mushrooms. Sylloge is still the only work of this kind that was both comprehensive for the botanical kingdom Fungi and reasonably modern. _What_mysteries_lay_in_spore_taxonomy_data_and_the_internationalization_of_mycology_in_Saccardo's_Sylloge_Fungorum
Many fungi produce toxins,[5] antibiotics,[6] and other secondary metabolites. For example, the cosmopolitan genus Fusarium and their toxins associated with fatal outbreaks of alimentary toxic aleukia in humans were extensively studied by Abraham Z. Joffe.[7]
Fungi are fundamental for life on earth in their roles as symbionts, e.g. in the form of mycorrhizae, insect symbionts, and lichens. Many fungi are able to break down complex organic biomolecules such as lignin, the more durable component of wood, and pollutants such as xenobiotics, petroleum, and polycyclic aromatic hydrocarbons. By decomposing these molecules, fungi play a critical role in the global carbon cycle.
Fungi and other organisms traditionally recognized as fungi, such as oomycetes and myxomycetes (slime molds), often are economically and socially important, as some cause diseases of animals (including humans) and of plants.[8]
Apart from pathogenic fungi, many fungal species are very important in controlling the plant diseases caused by different pathogens. For example, species of the filamentous fungal genus Trichoderma are considered one of the most important biological control agents as an alternative to chemical-based products for effective crop diseases management.[9]
Field meetings to find interesting species of fungi are known as 'forays', after the first such meeting organized by the Woolhope Naturalists' Field Club in 1868 and entitled "A foray among the funguses [sic]".[10]
Fungi and truffles are neither herbs, nor roots, nor flowers, nor seeds, but merely the superfluous moisture or earth, of trees, or rotten wood, and of other rotting things. This is plain from the fact that all fungi and truffles, especially those that are used for eating, grow most commonly in thundery and wet weather.
The Middle Ages saw little advancement in the body of knowledge about fungi. However, the invention of the printing press allowed authors to dispel superstitions and misconceptions about the fungi that had been perpetuated by the classical authors.[15]
The start of the modern age of mycology begins with Pier Antonio Micheli's 1737 publication of Nova plantarum genera.[16] Published in Florence, this seminal work laid the foundations for the systematic classification of grasses, mosses and fungi. He originated the still current genus names Polyporus[17] and Tuber,[18] both dated 1729 (though the descriptions were later amended as invalid by modern rules).
The founding nomenclaturist Carl Linnaeus included fungi in his binomial naming system in 1753, where each type of organism has a two-word name consisting of a genus and species (whereas up to then organisms were often designated with Latin phrases containing many words).[19] He originated the scientific names of numerous well-known mushroom taxa, such as Boletus[20] and Agaricus,[21] which are still in use today. During this period, fungi were still considered to belong to the plant kingdom, so they were categorized in his Species Plantarum. Linnaeus' fungal taxa were not nearly as comprehensive as his plant taxa, however, grouping together all gilled mushrooms with a stem in genus Agaricus.[22][23] Thousands of gilled species exist, which were later divided into dozens of diverse genera; in its modern usage, Agaricus only refers to mushrooms closely related to the common shop mushroom, Agaricus bisporus.[24] For example, Linnaeus gave the name Agaricus deliciosus to the saffron milk-cap, but its current name is Lactarius deliciosus.[25] On the other hand, the field mushroom Agaricus campestris has kept the same name ever since Linnaeus's publication.[26] The English word "agaric" is still used for any gilled mushroom, which corresponds to Linnaeus's use of the word.[24]
The term mycology and the complementary term mycologist are traditionally attributed to M.J. Berkeley in 1836.[27] However, mycologist appeared in writings by English botanist Robert Kaye Greville as early as 1823 in reference to Schweinitz.[28]
For centuries, certain mushrooms have been documented as a folk medicine in China, Japan, and Russia.[29] Although the use of mushrooms in folk medicine is centered largely on the Asian continent, people in other parts of the world like the Middle East, Poland, and Belarus have been documented using mushrooms for medicinal purposes.[30]
Mushrooms produce large amounts of vitamin D when exposed to ultraviolet (UV) light.[31] Penicillin, ciclosporin, griseofulvin, cephalosporin and psilocybin are examples of drugs that have been isolated from molds or other fungi.[32][33]
Yeasts are single-celled forms that reproduce by budding, whereas molds form multicellular hyphae. Dimorphic fungi grow as yeasts or spherules in vivo, as well as in vitro at 37C, but as molds at 25C. Dimorphism is regulated by factors such as temperature, CO2 concentration, pH, and the levels of cysteine or other sulfhydryl-containing compounds.
Conidia are asexual propagules (reproductive units) formed in various manners. Spores may be either asexual or sexual in origin. Asexual spores are produced in sac-like cells called sporangia and are called sporangiospores. Sexual spores include ascospores, basidiospores, oospores, and zygospores, which are used to determine phylogenetic relationships.
Asexual structures are referred to as anamorphs; sexual structures are known as teleomorphs; and the whole fungus is known as the holomorph. Two independent, coexisting classification systems, one based on anamorphs and the other on teleomorphs, are used to classify fungi.
Fungi are eukaryotic microorganisms. Fungi can occur as yeasts, molds, or as a combination of both forms. Some fungi are capable of causing superficial, cutaneous, subcutaneous, systemic or allergic diseases. Yeasts are microscopic fungi consisting of solitary cells that reproduce by budding. Molds, in contrast, occur in long filaments known as hyphae, which grow by apical extension. Hyphae can be sparsely septate to regularly septate and possess a variable number of nuclei. Regardless of their shape or size, fungi are all heterotrophic and digest their food externally by releasing hydrolytic enzymes into their immediate surroundings (absorptive nutrition). Other characteristics of fungi are the ability to synthesize lysine by the L-α-adipic acid biosynthetic pathway and possession of a chitinous cell wall, plasma membranes containing the sterol ergosterol, 80S rRNA, and microtubules composed of tubulin.
Fungi can use a number of different carbon sources to meet their carbon needs for the synthesis of carbohydrates, lipids, nucleic acids, and proteins. Oxidation of sugars, alcohols, proteins, lipids, and polysaccharides provides them with a source of energy. Differences in their ability to utilize different carbon sources, such as simple sugars, sugar acids, and sugar alcohols, are used, along with morphology, to differentiate the various yeasts. Fungi require a source of nitrogen for synthesis of amino acids for proteins, purines and pyrimidines for nucleic acids, glucosamine for chitin, and various vitamins. Depending on the fungus, nitrogen may be obtained in the form of nitrate, nitrite, ammonium, or organic nitrogen; no fungus can fix nitrogen. Most fungi use nitrate, which is reduced first to nitrite (with the aid of nitrate reductase) and then to ammonia.
Nonfungal organisms, including bacteria, synthesize the amino acid lysine by the meso-α,ε-diaminopimelic acid pathway (DAP pathway), whereas fungi synthesize lysine by only the L-α-adipic acid pathway (AAA pathway). Use of the DAP pathway is one of the reasons microorganisms previously considered to be fungi, such as the myxomycetes, oomycetes, and hyphochytrids, are no longer classified as fungi. The DAP and AAA biosynthetic pathways for lysine synthesis represent dichotomous evolution.
Many fungi, especially the yeasts, have soluble peptidomannans as a component of their outer cell wall in a matrix of α- and β-glucans. Mannans, galactomannans, and, less frequently, rhamnomannans are responsible for the immunologic response to the medically important yeasts and molds. Mannans are polymers of mannose or heteroglucans with α-D-mannan backbones. Structurally, mannan consists of an inner core, outer chain, and base-labile oligomannosides. The outer-chain region determines its antigenic specificity. Determination of mannan concentrations in serum from patients with disseminated candidiasis has proven a useful diagnostic technique.
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